Image sensors using photo diode pixels, for example implemented in a CMOS architecture, are known. An image sensor is a device comprising one or more radiation sensitive elements having an electrical property that changes when radiation is incident upon the radiation sensitive elements, together with circuitry for converting the changed electrical property into a signal. As an example, an image sensor may comprise a photo detector that generates a charge when radiation is incident on that photo detector. The photo detector may be designed to be sensitive to electromagnetic radiation in the range of (human) visible wavelengths, or other neighboring wavelength ranges, such as infrared or ultra violet, for example.
An array is made up of a number of pixels, each pixel having one or more radiation sensitive elements and optionally other circuitry. An array may comprise pixels arranged in a row and column configuration.